A team of researchers from the Perelman School of Medicine at the University of Pennsylvania has found that moderate to severe hot flashes continue, on average, for nearly five years after menopause, and more than a third of women experience moderate/severe hot flashes for ten years or more after menopause. Current guidelines recommend that hormone therapy, the primary medical treatment for hot flashes, not continue for more than five years. However, in the study published online in the journal Menopause, the authors write that “empirical evidence supporting the recommended three- to five-year hormone therapy for management of hot flashes is lacking.”

Hot flashes are episodes of intense radiating heat experienced by many women around the time of menopause. They can result in discomfort, embarrassment and disruption of sleep. Changing hormone levels are believed to cause hot flashes and other menopausal symptoms such as insomnia, fatigue, memory and concentration problems, anxiety, irritability and joint and muscle pain. In hormone therapy, medications containing female hormones replace the ones the body stops making during menopause. While hormone replacement therapy (HRT) is considered the most effective treatment for hot flashes, it is not appropriate for all women. In addition, concerns about health hazards linked to HRT have made some doctors less likely to prescribe it or to adhere strictly to recommended duration guidelines.

“Our findings point to the importance of individualized treatments that take into account each woman’s risks and benefits when selecting hormone or non-hormone therapy for menopausal symptoms,” said the study’s lead author, Ellen W. Freeman, research professor in the department of obstetrics and gynecology at Penn Medicine. “While leading non-hormone therapies such as Paxil or Escitalopram may provide some relief of menopausal symptoms for some women, for others, they may not be as effective as hormone-based therapy.”

In addition, obese white women and African-American women (both obese and non-obese) had the greatest risk of moderate/severe hot flashes during the period studied, whereas non-obese white women had the lowest risk. The increased risk of hot flashes in obese women has previously been associated with lower levels of estradiol (the most potent estrogen produced by women’s bodies) before menopause, but the new finding that non-obese African-American women also have a greater risk of hot flashes remains unexplained. An earlier report from the Study of Women’s Health Across the Nation indicated that African-American women may be more likely to report hot flashes and also have greater symptom sensitivity, suggesting that cultural differences may affect hot flash reporting, but further evidence is needed.

The Penn study also found a 34 percent lower risk of hot flashes among women with education beyond high school, a finding that researchers say also calls for additional study.

In addition to Dr. Freeman, other Penn co-authors are Mary D. Sammel, from the Center for Clinical Epidemiology and Biostatistics and Richard J. Sanders from the Center for Research on Reproduction and Women’s Health.

Bed Bug Hotspots in Philadelphia and Seasonal Trends

A study from Penn Medicine epidemiologists that looked at four years of bed bug reports of the city of Philadelphia found that infestations have been increasing and were at their highest in August and lowest in February. The findings, published in the Journal of Medical Entomology, point to two possible peak times to strike and eliminate the bugs.

“There is surprisingly very little known about seasonal trends among bed bug populations,” said Michael Z. Levy, assistant professor in the Center for Clinical Epidemiology and Biostatistics (CCEB), who mapped the bed bug hotspots in Philadelphia in an effort to find more effective ways to control them. “We found a steep and significant seasonal cycle in bed bug reporting and suspect that bed bugs have different levels of mobility depending on the season and that their population size may fluctuate throughout the year.”

Warm weather could be a driver for migration to other homes and breeding, he said. “We may be able to exploit this cycle: These seasonal trends could guide control programs to help reduce a city’s growing bug population,” he added.

To track the spatial and temporal patterns of the bugs, Dr. Levy and colleagues, including first author and research assistant Tarub S. Mabud, analyzed calls to the Philadelphia Department of Public Health’s Vector Control Services between 2008 and 2012. They then mapped the phone calls to get a clearer picture of the problem—when and where it was happening.
Reports came from all across the city, though south Philadelphia was the most affected by the bugs.

Overall, bed bug reports in the city steadily increased by 4.5 percent per month from 2008 to 2011, an almost 70 percent increase year to year. Nearly half of all pest infestations reported to the city over that time period were for bed bugs, a total of 382. From September 2011 to June 2012, Philadelphia residents made 236 reports of bed bug infestations, according to the study.

“We know the bug reports fluctuate over the year—what we need to figure out now is whether to treat when they are at their worst, in the summer months, or whether to wait until their numbers are down in the winter.” Dr. Levy said. “Seasonality, we noticed, is just one attribute that can eventually aid control measures, but it is one of many attributes we hope to uncover.”

While bed bugs likely migrate actively (i.e. crawl) over short distances, perhaps between adjacent rooms or houses, it’s likely they are starting new infestation hotspots throughout the city by riding on people or personal effects over longer distances, said Mr. Mabud.

The study is part of a larger, ongoing pilot study in Philadelphia aiming to come up with safer, cheaper and more effective ways to control bed bugs in an urban setting. These findings have led Dr. Levy and his team to south Philadelphia, where surveillance, tracking and treatment methods have begun.

Dr. Levy is also looking to his ongoing work in Peru, where the triatomine bug, a giant, often deadly insect has pervaded major cities. The bug carries the parasite Trypanosoma cruzi that causes Chagas disease, which can lead to fatal heart failure. Penn, along with its partner institution in Peru, Universidad Peruana Cayetano Heredia, was recently awarded $3 million by the National Institute of Allergy and Infectious Disease to conduct a five-year study to improve the control of Chagas disease in the city of Arequipa.

“In Peru, the Ministry of Health has been able to eliminate the insects from tens of thousands of people’s homes,” Dr. Levy said. “Bed bugs are different, and in many ways, more difficult to control. Still, my team is hoping to translate what works there for Philadelphia.”

Other co-authors from the CCEB include Alexis M. Barbarin, Corentin M. Barbu and Katelyn H. Levy, and Jason Edinger from Vector Control Services.

Liquid Crystal ‘Flowers’ That Can Be Used as Lenses

Researches from SEAS and SAS have made another advance in their effort to use liquid crystals as a medium for assembling structures.

In their earlier studies, the team produced patterns of “defects,” useful disruptions in the repeating patterns found in liquid crystals, in nanoscale grids and rings. The study, published in Physical Review X, adds a more complex pattern out of an even simpler template: a three-dimensional array in the shape of a flower.

And because the petals of this “flower” are made of transparent liquid crystal and radiate out in a circle from a central point, the ensemble resembles a compound eye and can thus be used as a lens.

The team consists of Randall Kamien, professor in the department of physics and astronomy in SAS; Kathleen Stebe, deputy dean for research and professor in chemical and biomolecular engineering in SEAS and Shu Yang, professor in departments of materials science and engineering and chemical and biomolecular engineering in SEAS. Members of their labs also contributed to the study, including lead author Daniel Beller, Mohamed Gharbi and Apiradee Honglawan.

The researchers’ ongoing work with liquid crystals is an example of a growing field of nanotechnology known as “directed assembly,” in which scientists and engineers aim to manufacture structures on the smallest scales without having to individually manipulate each component. Rather, they set out precisely defined starting conditions and let the physics and chemistry that govern those components do the rest.

“Before we were growing these liquid crystals on something like a trellis, a template with precisely ordered features,” Dr. Kamien said. “Here, we’re just planting a seed.” The seed, in this case, was silica beads—essentially, polished grains of sand. Planted at the top of a pool of liquid crystal, flower-like patterns of defects grow around each bead.

The key difference between the template in this experiment and ones in the research team’s earlier work was the shape of the interface between the template and the liquid crystal.

In their experiment that generated grid patterns of defects, those patterns stemmed from cues generated by the templates’ microposts. Domains of elastic energy originated on the flat tops and edges of these posts and travelled up the liquid crystal’s layers, culminating in defects. Using a bead instead of a post, as the researchers did in their latest experiment, makes it so that the interface is no longer flat.

Surface tension on the bead also makes it so these petals are arranged in a tiered, convex fashion. And because the liquid crystal can interact with light, the entire assembly can function as a lens, focusing light to a point underneath the bead.

“It’s like an insect’s compound eye, or the mirrors on the biggest telescopes,” said Dr. Kamien. “As we learn more about these systems, we’re going to be able to make these kinds of lenses to order and use them to direct light.”

This type of directed assembly could be useful in making optical switches and in other applications.